Patent GB-397645-A (GB)
Title: Improvements in and relating to machines for and methods of boring and reboring engine cylinders and the like
IPC: B23Q9/00
Filed: 1932-06-30
Abstract: 397,645. Boring-bar machines. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Van Norman Machine Tool Co. ; 160, Wilbraham Avenue, Springfield, Massa. chusetts, U.S.A.) June 30, 1932, No. 18562. [Class 83 (iii).] In a machine for re-boring engine cylinders, particularly for automobile engines, a boring head is guided during the first part of its axial feed by a sleeve surrounding the tool spindle and slidable in the frame of the machine, the subsequent guiding being effected by an expanding head on the sleeve which engages and slides along the re-bored part of the cylinder. The machine comprises a base 46, Fig. 2, carrying an electric motor 54 and a bearing post 96 in which is slidable a sleeve 88 moved axially by a pinion 188 and rack 186 and prevented from rotating by the rack 186 engaging a slot in the post 96. The toolspindle 84 is journalled without axial play in bearings 90, 98 in the sleeve 88 and is driven by toothed gears 78 from an extension 68 of the motor shaft 58 which is splined within a casing 66 attached to the sleeve 88. The base 46 is secured to a cylinder block B by means of a shoe 40 which is held to a cylinder adjacent the one being bored by a screw 36 having a head 38 located in a slot 42 in the shoe. The screw 36 is adjustable in a screwed bush 32, Fig. 6, which is rotatable on a head 24 and carries a screw 30 engaging a nut 26 slidable within the head 24. Bevelled surfaces 28 on the nut engage three grippers 22 radially mounted in the head and expanded to engage the cylinder on rotation of the socket 32. Shoulders 34 on the grippers take the end thrust. One end of the shoe 40 has lugs 53 straddling the base'46adjacent the spindle sleeve 88 and the other end has lugs 50 carrying screws 52 which engage on top of the base. On tightening the screws 52, the base is clamped against the cylinder block at opposite ends and an upward force is exerted on the head of the screw 36. The guiding head 156, Figs. 4 and 6, carries four radial plungers 154 to which are secured bolts 184 engaging internal screw threads on sleeves 164. Bevel gears 152 are connected to the sleeves 164 through lostmotion couplings and springs 180 whereby, should the plungers engage the cylinder walls unequally on expansion due to rotation of the bevel gears 152, the springs will be further tensioned and the pressure evenly distributed between the plungers. The bevel gears 152 are rotated simultaneously by a gear ring 148 rotatably mounted in the head and engaged by an elongated pinion on a vertical shaft journalled in the lower enlargement 92 of the sleeve 88 and in the gear casing 66, a knob for manipulation of the shaft being secured to the upper end thereof and being provided with dog teeth for engagement with similar @eth on a bush secured to the casing 66 to lock the plungers in the adjusted positions. The cutter head 100, Figs. 4 and 9, has projecting from its under side a pivot 104 carrying the tool-holder 102 which may be swung from the inoperative position shown in Fig. 9 into the cutting position, wherein the holder abuts against a shoulder 106 on the head. The cutte 108, preferably having a point 110 of tungsten carbide brazed thereto, is clamped in the holder by screws 116 and is held frictionally by a spring 112 whilst being adjusted to the correct diameter of cut by means of a micrometer 116a, the end 120 of which can be clamped in a hole 122 in the base by a screw 128. In operation, the clamp head 24 is inserted in a cylinder adjacent the one to be re-bored and is secured thereto by rotating the socket 32 to expand the grippers 22. The head 38 of the screw 36 is adjusted to the correct height and the shoe 40 is then slid into engagement therewith. The base 46 is next slid on to the shoe, the sleeve 88 lowered by rotating the pinion 188 through a handwheel and clutch until the guiding head 156 is located in the cylinder to be re-bored and the plungers 154 are expanded by rotating the gear 148, the cutter 108 being in the retracted position. The base 46 is then clamped to the cylinder block by rotation of the screws 52, the guiding head released and the sleeve 88 withdrawn to enable the cutter to be adjusted by the micrometer 116a and clamped by operating the screws 116 through an aperture 132, Fig. 9, in the base 46. The boring operation is then commenced by rotating the toolspindle 84 and feeding the sleeve 88 through a double worm drive from a worm 60, Fig. 2, on the motor shaft 58 to a worm wheel loose on the pinion shaft 190 but connectible thereto by a clutch, the hand clutch being disconnected. The enlarged portion 92 of the sleeve 88 guides the cutter head until the guiding head 156 enters the cylinder, whereupon the plungers 154 are expanded into contact with the bored portion of the cylinder by operating the vertical shaft in the sleeve 88 whilst the spindle 84 is rotating.